(1) Field of the Invention
This invention relates to a muffler for work vehicle V-type engines.
(2) Description of the Prior Art
To reduce the noisy sound of the exhaust gases as they escape at high speed the exhaust pipes of V-type engines in work vehicles such as a tractor, power lawn mower, riding-type sprinkler and combine, various types of mufflers have so far been proposed in the prior art. Referring to FIG. 3, a typical conventional muffler 3, which is represented by laid-open Japanese utility model application No. 53-50317, is supported in a lengthwise position in the bottom of the chassis 1 of the vehicle, with its axis laid parallel with the centerline of the vehicle.
The exhaust pipe consists of an L-shaped inlet pipe 5 and an exhaust manifold 4. The inlet pipe 5 has its lower end connected to the inlet port of the muffler 3 and extends upward through the chassis 1 to put its upper end 5a for connection to the lower end 4a of the exhaust manifold 4. The inlet pipe 5 is connected to the exhaust manifold 4, not directly, but through a flexible corrugated connector 6, which is intended to prevent direct propagation of the vibrations from the muffler 3 to the engine while the vehicle is running on the road, since the muffler 3, mounted on the chassis 1, is subject to the vibrations owing to the conditions of the road surface. The exhaust pipe 4 consists of branched end portions 9 and 10 for connection to the separate combustion chambers of the two cylinders in work vehicle V-type engines.
However, those prior art mufflers have been found to have various difficulties. For example, in those work vehicles in which their V-type engine is mounted in a sidewise position, with the axis of the crankshaft laid perpendicularly with the longitudinal axis of the chassis, the arrangement is sometimes such that the one end portion 9 diverges from the extreme end of the exhaust pipe 4 while the other portion 10 branches off from it at a point some distance down from the junction where the portion 9 is joined to the exhaust pipe 4. This configurational asymmetry of the end portions 9 and 10 with respect to the exhaust pipe 4 has been proved to constitute a cause of imbalance in the output and exhaust efficiency of the cylinders 7 and 8.
Furthermore, in applications where the muffler 3 is mounted in a lengthwise position, as in FIG. 3, the muffler 3 stands with its side of the smaller surface area oriented in the direction of movement of the vehicle, which means a rather reduced cooling effect in the flow of air generated by the moving vehicle. This is not advantageous, since cooling helps a muffler to reduce the exhaust noise.
In addition, the provision of the flexible corrugated connector 6 makes the entire exhaust pipe system undesirably great in size, and extend in the vicinity of the engine fuel system and air intake device, exposing them to a constant danger of heating by the higher surface temperature of the exhaust pipe system when exhaust gases are flowing therethrough.
The present invention has been proposed to eliminate the above problems.